Modern society is a computerized society. Examples of systems using computers include: an information system mainly used in an office or the like; and an industrial control system (“ICS”) used in a power plant, a pipeline, a chemical plant, or the like. Each individual ICS is made of a distinct system specific to the corresponding industry.
Most ICSs are systems mainly used in systems providing infrastructures, and accordingly, faults or anomalies are likely to cause serious human and economic damage. There are also systems in which several ICSs are connected via a network and exchange information with each other. In the case where data of an ICS having an anomaly is sent to other ICSs in such an environment of operating a plurality of ICSs, it is desirable that the receiving ICSs are kept from being significantly affected.
When operating a plurality of ICSs, the determination of whether or not a specific ICS has an anomaly imposes load on IT resources and also requires processing time, so that the ICS system itself may not be able to perform anomaly determination. Also, for typical information systems, it is possible to constantly perform anomaly determinations and, if there is a suspected system, to isolate the system offline and operate the other systems. However, this may be difficult for ICSs that are supposed to operate continuously.
For example, Japanese Unexamined Patent Publication No. 2000-214919 discloses a configuration control means that executes a procedure of minimizing functional loss of its own device according to anomaly information in the case where a monitored device has an anomaly. However, the disclosed technique is premised on two similar systems, namely, a master and a slave, in the case of an anomaly, and is not applicable to a plurality of ICSs which are different, distinct systems are connected via a network.